I have the Bionx system and I have mixed feelings about it.
Pros:
- Got me back into riding regularly
- Gives me more consistent commute times when I'm tired
- Shaves some time off my commute, which is longer than average
- If I wake up and I have tired legs I'll still take the bike knowing the motor will bail me out
Cons:
- Expensive. I wanted something turnkey so I bought it, but other DIY systems are much cheaper
- The weight really affects the bike handling. I almost wiped out in a corner because the weight distribution of the bike is upset
- Going up steep hills you have to use level 2 just to offset the weight of the system
If faced with the same decision today I'm not sure I'd buy it again. Of course I'm not sure that I wouldn't buy it again either. But, I think if I was advising someone interested in getting an ebike and they didn't mind a little DIY I'd advise them to put together their own system. If you want turnkey then Bionx works well. The system has worked perfectly from day 1 and zero glitches.